[Java] JavaIO - (3)Data, ByteArray, StringReaderWriter

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;

public class _09_DataIOExam {
    public static void main(String[] args) throws Exception{
        //문제 - 이름, 국어, 영어, 수학, 총점, 평균 점수를 /tmp/score.dat 파일에 입력하시오.
        String name = "Kim";
        int kor = 90;
        int eng = 85;
        int math = 95;
        int total = kor + eng + math;
        double average = (double)(total / 3);

        //여러 타입을 읽고 씀
        DataOutputStream out = new DataOutputStream(new FileOutputStream("/tmp/score.dat"));
        out.writeUTF(name);
        out.writeInt(kor);
        out.writeInt(eng);
        out.writeInt(math);
        out.writeInt(total);
        out.writeDouble(average);
        out.close();

        // /tmp/score.dat 파일을 출력하시오.
        DataInputStream in = new DataInputStream(new FileInputStream("/tmp/score.dat"));
        String readName = in.readUTF();
        int readKor = in.readInt();
        int readEng = in.readInt();
        int readMath = in.readInt();
        int readTotal = in.readInt();
        double readAverage = in.readDouble();
        in.close();
        System.out.println(readName + readKor + readEng + readMath + readTotal + readAverage);


    }
}

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

public class _10_ByteArrayIOExam {
    public static void main(String[] args) throws Exception {
        //ByteArray에 쓰기
        int data1 = 1;
        int data2 = 2;

        ByteArrayOutputStream out = new ByteArrayOutputStream(); //메모리상에 ByteArray 데이터가 저장된다.
        out.write(data1); //data1의 마지막 1byte에 저장한다.
        out.write(data2);
        out.close();

        byte[] byteArray = out.toByteArray(); //메모리상에 저장된 byte배열을 return 해준다.
        System.out.println(byteArray.length);
        System.out.println(byteArray[0]);
        System.out.println(byteArray[1]);

        System.out.println();
        System.out.println("----------------------");
        System.out.println();

        //ByteArray 읽어들이기
        byte[] array = new byte[2];
        array[0] = (byte)1;
        array[1] = (byte)2;
        ByteArrayInputStream in = new ByteArrayInputStream(array); //byt
        int read1 = in.read();
        int read2 = in.read();
        int read3 = in.read();

        in.close();

        System.out.println(read1);
        System.out.println(read2);
        System.out.println(read3);
        System.out.println(array[0]);
        System.out.println(array[1]);

        //charArrayReader, charArrayWriter도 비슷한 방법응로 사용가능

    }
}

import java.io.StringReader;
import java.io.StringWriter;

public class _11_StringReaderWriter {
    public static void main(String[] args) throws Exception{
        //쓰기
        StringWriter out = new StringWriter(); //생성자가 없는 것은 보통 메모리에 쓰여진다고 생각하면 쉽다.
        out.write("Hello");
        out.write(" ");
        out.write("World");
        out.write("!!!");

        out.close();

        String writeResult = out.toString();
        System.out.println(writeResult);

        System.out.println();
        System.out.println("------------------------");
        System.out.println();

        //읽기
        String readResult = "Hello to World!";
        StringReader in = new StringReader(readResult);
        int i = -1;
        while ((i = in.read()) != -1) {
            System.out.print((char)i);
        }

        in.close();


    }
}